COOL-07, Water Pump Information and Replacement

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Tools Needed

Other Procedures Needed


There are two different styles of water pumps used on the 924S and 944 (including Turbos). The new style coolant pump has a guard rail for the timing belt an a larger idler roller (46.2 mm vs. 32.0 mm). The new style was installed on all cars produced after July 1986. I recommend installing the new style pump when replacing the water pump. For cars which previously did not have the new style pump installed, this requires modifying the rear timing cover and purchasing a belt guard and larger idler roller. Some of the new style pumps will come with the belt guard already installed so ask your parts supplier when ordering. The groove for the thermostat snap ring has also been moved. Previously, it was 4.5 mm from the sealing surface and is now at 7 mm. This requires the use of a new thermostat and spacer.

On Turbocharged cars, there is a nozzle on the water pump which supplies cooling water to the turbocharger bearing housing. On Normally Aspirated cars the nozzle is a block-off plate. The block-off plate / nozzle is sealed to the water pump by an o-ring which should be replaced when the new pump is installed. On some pumps, the block-off plate / nozzle is mounted using a 6 mm stud and nut and a 6 mm x 20 mm bolt. However, most of the new pumps come with two bolt holes. This requires transferring the 6 mm stud from the old pump to the new one or purchasing another 6 mm x 20 mm bolt.

Part Numbers

Model Old Style Pump New Style Pump
924S, 944, 944S 944 106 021 13 951 106 021 10
944 Turbo 951 106 021 01 951 106 021 10

Other Parts

New Style Pump Part Number
Water Pump Gasket 1 944 106 132 04
Guard Rail 944 105 213 01
Guard Rail Lock Nuts (2) 999 084 092 02
46.2 mm Roller 944 105 241 03
Block-off Plate / Nozzle Part Number
Block-off plate (NA cars only) 944 106 313 00
Nozzle (Turbo Only) 951 106 313 00
Thermostat for Turbocharger 951 106 311 00
O-Ring (NA or Turbo) 900 174 049 40 or 999 707 283 40
Washer (2) N 011 524 7
Bolts 6 mm x 20 mm (2) N 014 704 1
Thermostat Part Number
Thermostat (New) 944 106 019 00
Thermostat (Old) 944 106 129 05
Spacer (New Style Pump) 900 234 160 00
O-Ring (New Thermostat) 944 106 929 08
O-Ring (Old Thermostat) 944 106 929 05
Thermostat Snap Ring 900 042 025 01

1 Normally, a new gasket will be provided with any new or rebuilt water pump. However, when ordering your pump, you should ask if the gasket is included.


  1. Place car on jack stands or ramps.
  2. Disconnect battery positive lead.
  3. Using ENG-13, set engine at TDC on cylinder number 1.
  4. Using ENG-03, remove the starter and install the flywheel lock (P9206).
  5. Using ENG-05, remove the balance shaft belt, timing belt, rollers, balance shaft sprockets, crankshaft gear, and rear timing cover.
  6. Using COOL-02, drain the cooling system to an appropriate catch pan.
  7. Disconnect the coolant hoses from the water pump.
  8. Loosen the water pump retaining bolts and nuts (10 mm socket) and remove the water pump from the car.

    Tip: This is a good time to inspect and replace the crankshaft and balance shaft oil seals.

  9. Install thermostat on new water pump using Snap Ring from old pump.

    On the newer style water pump, the gap between the thermostat sealing surface and the snap ring groove is 7mm. This will require the newer style thermostat and sealing ring. It will also require installation of the 2.5mm support washer between the snap ring and the thermostat. The older style water pump has a 4.5mm gap between the thermostat sealing surface and the snap ring groove and requires the older style thermostat and sealing ring without the support washer.

  10. On Turbocharged cars install the turbocharger thermostat and thermostat nozzle with o-ring on new water pump.
  11. On Normally Aspirated cars install the Block-off nozzle with o-ring on the new water pump.
  12. Install the new water pump using a new gasket (normally supplied with the pump).



    The factory manual has you install the water pump fasteners using Loctite 270. This is fine for the nuts. However, I prefer to not use it on the bolts as is increases the probability of stripping the bolts holes during the next removal.

  13. Tighten the water pump nuts and bolts to 8 Nm (6 ft-lbs).
  14. Using ENG-06 install the timing belt, balance shaft belt and all rollers. The belts are tensioned during the performance of ENG-06 using ENG-10.
  15. Install the air filter assembly (AF-01).
  16. Reconnect battery.
  17. Using COOL-02, fill and vent the cooling system.
  18. Install skid pan.
  19. Remove car from jack stands/ramps.

Clark's Garage © 1998